1. Field of the Invention
The present invention relates to a semiconductor device and a semiconductor device manufacturing method and, more particularly, a semiconductor device and a semiconductor device manufacturing method for forming an interlayer insulating film containing a coating insulating film having a low dielectric constant.
2. Description of the Prior Art
In recent years, the multi-layered wiring structure using the interlayer insulating film having the low dielectric constant is employed with the higher integration degree and the higher density of the semiconductor integrated circuit devices. In such case, the coating insulating film that is excellent in flatness and has the low relative dielectric constant is often employed as the interlayer insulating film.
The coating insulating film having the low relative dielectric constant can be obtained by coating the coating liquid containing the silicon-containing inorganic compound or the coating liquid containing the silicon-containing organic compound on the film forming surface by the spin coating method and then removing the solvent in the coating liquid by the heating.
However, the coating insulating film contains a large amount of moisture in the film and has the high hygroscopicity. Also, the strength of the coating insulating film itself is relatively low. Since the coating insulating film has a poor adhesiveness with a CVD (Chemical Vapor Deposition) film or a metal wiring layer, there is a fear of resulting in peeling-off of the film.
In order to compensate the weak point of the coating insulating film, such a structure is often employed that a cap layer (upper protection layer) and a liner layer (lower protection layer) containing Si and N or Si and C are formed on and under the coating insulating film to wrap the coating insulating film therein.
The semiconductor device having a multi-layered wiring comprises an interlayer insulating film that is formed between the upper and lower wirings by laminating in order the lower protection layer containing Si and N or Si and C, the coating insulating film and the upper protection layer containing Si and N or Si and C.
However, since the insulating film containing Si and N has a high relative dielectric constant, the entire interlayer insulating film results in having a higher dielectric constant even if employing the lower and upper protection layers of thinner thickness.
It is difficult for the lower and upper protection layers containing Si and C to sufficiently suppress an increase of a leakage current while the lower and upper protection layers containing Si and C have lower relative dielectric constants than the lower and upper protection layers containing Si and N.
In addition, it is impossible to say that the adhesiveness between the coating insulating film and the lower and upper protection layers containing Si and N or Si and C is good, and thus the barrier characteristic to the moisture, etc. is not perfect.
On the other hand, there is an occasion where the other lower and upper protection layers are formed on the lower and upper surfaces of the coating insulating film using a plasma enhanced chemical vapor deposition method (hereinafter, referred to as PE-CVD method). PE-CVD method is capable of film-forming at a relatively lower range of temperature while using a gas containing SiH4 and N2O, a gas containing SiH4 and O2, or a gas containing TEOS and O2 as a film-forming gas in order to improve the adhesiveness.
However, in the other lower and upper protection layers, there are problems as follows for the reasons why the adhesiveness to the coating insulating film and a mechanical strength of the film itself is not sufficient, and a gas having a strong oxidizing reaction is employed.
(i) There arises the peeling-off of the coating insulating film at an interface between the coating insulating film and the lower or upper protection layer.
(ii) The laminated structure in the semiconductor device is destroyed through the destroy of the lower protection layer as a stopper which serves as a framework (for reinforcement) during processing, especially CMP (Chemical mechanical Polishing).
(iii) At a formation of the upper protection layer, the usage of the film-forming gas including the gas having the strong oxidizing reaction results in an increase of the dielectric constant due to an oxidization of the coating insulating film.
It is an object of the present invention to provide a semiconductor device and a semiconductor device manufacturing method, in a cover insulating film constituted by a coating insulating film and a protection layer for covering an upper surface or a lower surface of the coating insulating film, or in an interlayer insulating film constituted by a coating insulating film and a protection layer for covering an upper surface and a lower surface of the coating insulating film, capable of forming the cover insulating film or the interlayer insulating film that can achieve a lower dielectric constant as a whole, has a more complete barrier characteristic to the moisture, or the leakage current, etc., and is excellent in flatness.
It is another object of the present invention to provide a semiconductor device and a semiconductor device manufacturing method capable of improving an adhesiveness between the protection layer and the coating insulating film and a mechanical strength of the protection layer itself.
Advantages that are achieved by a configuration of the present invention will be explained as follows.
In the present invention, a protection layer is formed to cover a coating insulating film by plasmanizing a first film forming gas to react, wherein the first film forming gas consists of any one selected from a group consisting of alkoxy compound having Sixe2x80x94H bonds and siloxane having Sixe2x80x94H bonds and any one oxygen-containing gas selected from a group consisting of O2, N2O, NO2, CO, CO2, and H2O.
According to the experiment made by the inventors of the present invention, it is found that the silicon-containing insulating film formed by plasmanizing the first film forming gas to react has a good adhesiveness to the coating insulating film, is dense to the same extent as the silicon nitride film, is excellent in the water resistance, and contains the small content of moisture in the film.
In this manner, the plasma CVD insulating film according to the present invention has the good adhesiveness to the coating insulating film and also has the density equivalent to the silicon nitride film. Therefore, when the plasma CVD insulating film according to the present invention is formed to come into contact with the coating insulating film and to cover the coating insulating film like the configuration of the present invention, there can be obtained the cover insulating film that can have the more complete barrier characteristic to the entering of the moisture into the coating insulating film from the outside and to the flowing-out of the moisture to the outside, while being excellent in flatness.
Also, the plasma CVD insulating film according to the present invention has the lower relative dielectric constant than the silicon nitride film in addition to the above characteristics. The protection layer made of the plasma CVD insulating film according to the present invention are formed on at least any one of an upper surface and a lower surface of the coating insulating film which serves as the main cover insulating film or the main interlayer insulating film and has the low relative dielectric constant. There can be obtained the cover insulating film or interlayer insulating film that has more completely the barrier characteristic to the entering/flowing-out of the moisture into/from the coating insulating film, the barrier characteristic to the leakage current, etc. and also achieves the low dielectric constant as a whole.
In this manner, according to the present invention, there can be obtained the cover insulating film or interlayer insulating film that can achieve the lower dielectric constant as a whole, has a barrier characteristic to the entering/flowing-out of the moisture into/from the coating insulating film and a barrier characteristic to the leakage current, etc. more completely, and is excellent in flatness.
The silicon-containing insulating film of the present invention has a peak of the absorption intensity of the infrared rays in a range of the wave number 2270 to 2350 cmxe2x88x921, a film density in a range of 2.25 to 2.40 g/cm3, and a relative dielectric constant in a range of 3.3 to 4.3.
According to the experiment of the inventors of this application, it is found that the silicon-containing insulating film having such characteristics has the high mechanical strength, is dense, is excellent in the water resistance, and has the small amount of contained moisture in the film like the silicon nitride film, and has the relative dielectric constant smaller than the silicon nitride film. Further, it is found that the silicon-containing insulating film has a good adhesiveness to the coating insulating film.
Therefore, if the silicon-containing insulating film having aforementioned characteristics is employed as the protection layer for covering the wirings, etc., the corrosion of the wiring can be prevented by blocking a penetration of the incoming moisture into the semiconductor device, while the parasitic capacitance between the wirings can be reduced.
Also, the upper and lower wirings and the interlayer insulating film interposed between the upper and lower wirings are provided on the substrate. The interlayer insulating film is constructed by laminating in order from the bottom the lower protection layer formed of the silicon-containing insulating film according to the present invention, the main insulating film, and the upper protection layer formed of the silicon-containing insulating film according to the present invention.
The silicon-containing insulating film having aforementioned characteristics has a good adhesiveness with the coating insulating film, and has the high mechanical strength. Therefore, the laminated structure is prevented from a destroy such as a peeling-off of the films, etc., even if a mechanical shock is applied to the laminated structure from outside.
The silicon-containing insulating film having aforementioned characteristics is dense. Therefore, the moisture contained in the coating insulating film can be prevented from flowing out to the peripheral portions of the silicon-containing insulating film.